Driver transition assistance for transitioning to manual control for vehicles with autonomous driving modes

ABSTRACT

Aspects of the disclosure relate to controlling a transition between a manual driving mode and an autonomous driving mode of a vehicle. For instance, one or more processors of one or more control computing devices may control the vehicle in the autonomous driving mode. While controlling the vehicle in the autonomous driving mode and decelerating at a given rate, the processors may receive at a user input of the vehicle input requesting a transition from the autonomous driving mode to the manual driving mode. In response to the input, the processors may transition the vehicle to the manual driving mode. After transitioning the vehicle to the manual driving mode, the processors may send deceleration signals to a deceleration actuator thereby causing the vehicle to continue to decelerate at the given rate.

BACKGROUND

Some vehicles may operate in various modes which provide differentlevels of control to a driver. For instance, typical vehicles mayoperate in manual driving modes, where a driver controls acceleration,deceleration, and steering of the vehicle as well as semiautonomousmode, such as cruise control, where computing devices of the vehiclecontrol acceleration and deceleration while a driver controls steering,etc. In some instances, these vehicles may also operate in autonomousdriving modes where the computing devices of the vehicle controls all ofbraking, all of the acceleration, deceleration and steering of thevehicle without continuous input from a driver or passenger. In theautonomous mode, the passenger may provide some initial input, such as adestination location, and the vehicle maneuvers itself to thatdestination.

Typically when operating in an autonomous mode, where the human driverhas no input on the control of the vehicle's acceleration, decelerationor steering, a switch to manual mode can be made using input at asteering wheel, acceleration or deceleration pedal, or other some otheruser input. When using one of these inputs to change modes, there is aninherent delay between the time when the driver uses the input to whenthe vehicle's control computing devices (which control the vehicle inthe autonomous driving mode) completely release control of theacceleration, deceleration and steering. In order to allow a safetransition where the driver is guaranteed control of the vehicle this“transition” may effectively cause the vehicle's control computingdevices to immediately cease sending signals to the acceleration,deceleration, and steering systems of the vehicle.

BRIEF SUMMARY

One aspect of the disclosure provides a method of controlling atransition between a manual driving mode and an autonomous driving modeof a vehicle. The method includes controlling, by one or more processorsof one or more control computing devices, the vehicle in the autonomousdriving mode; while controlling the vehicle in the autonomous drivingmode and decelerating at a given rate, receiving, by the one or moreprocessors at a user input of the vehicle, input requesting a transitionfrom the autonomous driving mode to the manual driving mode; in responseto the input, transitioning the vehicle to the manual driving mode; andafter transitioning the vehicle to the manual driving mode, sending, bythe one or more processors, deceleration signals to a decelerationactuator thereby causing the vehicle to continue to decelerate at thegiven rate.

In one example, the method also includes, after receiving the input,determining that the one or more control computing devices are currentlycausing the vehicle to deceleration, and wherein sending thedeceleration signals is based on the determination that the controlcomputing devices are currently causing the vehicle to deceleration. Inthis example, the method also includes, after determining that the oneor more control computing devices are currently causing the vehicle todeceleration, comparing an amount of deceleration currently requested bythe control computing devices to a threshold deceleration, and whereinsending the deceleration signals is further based on the comparison. Inanother example, the method also includes, identifying a distance thatuser input has moved to cause the input, and wherein the decelerationsignals are sent further based on the distance. In another example, themethod also includes, identifying a force on the user input to cause theinput, and wherein the deceleration signals are sent further based on amagnitude of the force. In another example, the deceleration signals aresent according to a current plan of operation by the one or more controlcomputing devices when that the input is received. In another example,the method also includes continuing to send the deceleration signals tothe deceleration actuator until a deceleration signal initiated by inputat a deceleration pedal of the vehicle reaches the decelerationactuator. In another example, the method also includes continuing tosend the deceleration signals to the deceleration actuator until anacceleration signal initiated by user input at a deceleration pedal ofthe vehicle reaches an acceleration actuator of the vehicle that causesthe vehicle to accelerate. In another example, the user input is asteering wheel of the vehicle. In another example, the user input is abrake pedal of the vehicle. In another example, while controlling thevehicle in the autonomous driving mode and decelerating at the givenrate, the vehicle is also changing orientation at a second given rate,and wherein the method further comprises, after transitioning thevehicle to the manual driving mode, sending, by the one or moreprocessors, steering orientation signals to a steering actuator therebycausing the vehicle to continue to change orientation at the secondgiven rate.

Another aspect of the disclosure provides a system for controlling atransition between a manual driving mode and an autonomous driving modeof a vehicle. The system comprising one or more processors configured tocontrol the vehicle in the autonomous driving mode; while controllingthe vehicle in the autonomous driving mode and decelerating at a givenrate, receive, at a user input of the vehicle, input requesting atransition from the autonomous driving mode to the manual driving mode;in response to the input, transition the vehicle to the manual drivingmode; and after transitioning the vehicle to the manual driving mode,send deceleration signals to a deceleration actuator thereby causing thevehicle to continue to decelerate at the given rate.

In one example, the one or more processors are further configured to,after receiving the input, determine that the one or more controlcomputing devices are currently causing the vehicle to deceleration, andwherein sending the deceleration signals is based on the determinationthat the one or more control computing devices are currently causing thevehicle to deceleration. In this example, the one or more processors arefurther configured to, after determining that the one or more controlcomputing devices are currently causing the vehicle to deceleration,compare an amount of deceleration currently requested by the one or morecontrol computing devices to a threshold deceleration, and whereinsending the deceleration signals is further based on the comparison. Inanother example, the one or more processors are further configured to,identify a distance that user input has moved to cause the input, andwherein the deceleration signals are sent further based on the distance.In another example, the one or more processors are further configured toidentify an amount of force on the user input to cause the input, andwherein the deceleration signals are sent further based on the amount offorce. In another example, the one or more processors are furtherconfigured to continue to send the deceleration signals to thedeceleration actuator until a deceleration signal initiated by input ata deceleration pedal of the vehicle reaches the deceleration actuator.In another example, the one or more processors are further configured tocontinue to send the deceleration signals to the deceleration actuatoruntil an acceleration signal initiated by user input at a decelerationpedal of the vehicle reaches an acceleration actuator of the vehiclethat causes the vehicle to accelerate. In another example, whilecontrolling the vehicle in the autonomous driving mode and deceleratingat the given rate, the vehicle is also changing orientation at a secondgiven rate, and the one or more processors are further configured to,after transitioning the vehicle to the manual driving mode, sendsteering orientation signals to a steering actuator thereby causing thevehicle to continue to change orientation at the second given rate. Inanother example, the system also includes the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional diagram of an example vehicle in accordance withan exemplary embodiment.

FIG. 2 is an example of map information in accordance with aspects ofthe disclosure.

FIG. 3 is an example external view of a vehicle in accordance withaspects of the disclosure.

FIG. 4 is an example bird's eye view of a geographic area in accordancewith aspects of the disclosure.

FIG. 5 is an example functional diagram in accordance with aspects ofthe disclosure.

FIG. 6 is another example functional diagram in accordance with aspectsof the disclosure.

FIG. 7 is an example flow diagram in accordance with aspects of thedisclosure.

DETAILED DESCRIPTION

Overview

Vehicles may have many different modes of operation including manual andautonomous driving modes as well as various modes there between. Asnoted above, when operating in an autonomous mode, where the humandriver has no input on the control of the vehicle's acceleration,deceleration or steering, a switch to manual mode can be made usinginput at a steering wheel, acceleration or deceleration pedal, or othersome other user input. In some instances, the transition from theautonomous driving mode to the manual driving mode may occur while thevehicle's control computing devices are sending signals to the actuatorsof the steering, acceleration or deceleration systems. For instance,signals may be sent to the vehicle's one or more deceleration actuatorsto decelerate or cause the vehicle to brake in order to reduce the speedof the vehicle.

When these signals are ceased during the transition, the resultingreduction in deceleration of the vehicle can actually feel to the driveras if the vehicle is inappropriately understeering, deceleration oraccelerating depending upon the situation. This can be especiallyuncomfortable for a driver where the transition is a result of thedriver feeling the need to take control of the vehicle in a situation inwhich the driver feels additional braking is necessary (i.e. the driveris concerned that a collision may occur, etc.).

In order to assist the driver during this transition period, additionalsteering, acceleration and/or deceleration signals may be sent to thevehicle's various actuators. These signals may actually continue duringand after the transition period until the control computing devicesrecognize the driver's intention or desire to disengage the autonomousmode before or when the driver commanded steering, acceleration, orbraking reaches the same magnitude as the control computing devices werepreviously commanding. This timing can be tuned to feel “natural” andcomfortable to a driver. In addition, this reduces the feeling that thevehicle is understeering, decelerating, or accelerating when the driveris given control of the vehicle.

The features described herein may allow for a smooth transition from anautonomous driving mode to a manual driving mode. In other words, asnoted above, when the vehicle is changing the orientation of the vehicle(steering), decelerating, or accelerating at the time of the transition,these features may greatly reduce the discomfort of a driver caused by afeeling of inappropriate acceleration of the vehicle. This alsomaterially reduces stopping distance in the event of an emergency orforceful driver takeover since the vehicle does not drop brakingpressure for the time between when the transition is detected and whenthe driver pushes the pedal to its maximum displacement.

Example Systems

As shown in FIG. 1, a vehicle 100 in accordance with one aspect of thedisclosure includes various components. While certain aspects of thedisclosure are particularly useful in connection with specific types ofvehicles, the vehicle may be any type of vehicle including, but notlimited to, cars, trucks, motorcycles, buses, recreational vehicles,etc. The vehicle may have one or more computing devices, such ascomputing devices 110 containing one or more processors 120, memory 130and other components typically present in general purpose computingdevices.

The memory 130 stores information accessible by the one or moreprocessors 120, including instructions 134 and data 132 that may beexecuted or otherwise used by the processor 120. The memory 130 may beof any type capable of storing information accessible by the processor,including a computing device-readable medium, or other medium thatstores data that may be read with the aid of an electronic device, suchas a hard-drive, memory card, ROM, RAM, DVD or other optical disks, aswell as other write-capable and read-only memories. Systems and methodsmay include different combinations of the foregoing, whereby differentportions of the instructions and data are stored on different types ofmedia.

The instructions 134 may be any set of instructions to be executeddirectly (such as machine code) or indirectly (such as scripts) by theprocessor. For example, the instructions may be stored as computingdevice code on the computing device-readable medium. In that regard, theterms “instructions” and “programs” may be used interchangeably herein.The instructions may be stored in object code format for directprocessing by the processor, or in any other computing device languageincluding scripts or collections of independent source code modules thatare interpreted on demand or compiled in advance. Functions, methods androutines of the instructions are explained in more detail below.

The data 132 may be retrieved, stored or modified by processor 120 inaccordance with the instructions 134. For instance, although the claimedsubject matter is not limited by any particular data structure, the datamay be stored in computing device registers, in a relational database asa table having a plurality of different fields and records, XMLdocuments or flat files. The data may also be formatted in any computingdevice-readable format.

The one or more processor 120 may be any conventional processors, suchas commercially available CPUs. Alternatively, the one or moreprocessors may be a dedicated device such as an ASIC or otherhardware-based processor. Although FIG. 1 functionally illustrates theprocessor, memory, and other elements of computing devices 110 as beingwithin the same block, it will be understood by those of ordinary skillin the art that the processor, computing device, or memory may actuallyinclude multiple processors, computing devices, or memories that may ormay not be stored within the same physical housing. For example, memorymay be a hard drive or other storage media located in a housingdifferent from that of computing devices 110. Accordingly, references toa processor or computing device will be understood to include referencesto a collection of processors or computing devices or memories that mayor may not operate in parallel.

Computing devices 110 may all of the components normally used inconnection with a computing device such as the processor and memorydescribed above as well as a user input 150 (e.g., a mouse, keyboard,touch screen and/or microphone) and various electronic displays (e.g., amonitor having a screen or any other electrical device that is operableto display information). In this example, the vehicle includes aninternal electronic display 152 as well as one or more speakers 154 toprovide information or audio visual experiences. In this regard,internal electronic display 152 may be located within a cabin of vehicle100 and may be used by computing devices 110 to provide information topassengers within the vehicle 100.

Computing devices 110 may also include one or more wireless networkconnections 156 to facilitate communication with other computingdevices, such as the client computing devices and server computingdevices described in detail below. The wireless network connections mayinclude short range communication protocols such as Bluetooth, Bluetoothlow energy (LE), cellular connections, as well as various configurationsand protocols including the Internet, World Wide Web, intranets, virtualprivate networks, wide area networks, local networks, private networksusing communication protocols proprietary to one or more companies,Ethernet, WiFi and HTTP, and various combinations of the foregoing.

In one example, computing devices 110 may be control computing devicesof an autonomous driving computing system or incorporated into vehicle100. The autonomous driving computing system may capable ofcommunicating with various components of the vehicle in order to controlthe movement of vehicle 100 according to primary vehicle control code ofmemory 130. For example, returning to FIG. 1, computing devices 110 maybe in communication with various systems of vehicle 100, such asdeceleration system 160, acceleration system 162, steering system 164,signaling system 166, navigation system 168, positioning system 170,perception system 172, and power system 174 (i.e. the vehicle's engineor motor) in order to control the movement, speed, etc. of vehicle 100in accordance with the instructions 134 of memory 130. Again, althoughthese systems are shown as external to computing devices 110, inactuality, these systems may also be incorporated into computing devices110, again as an autonomous driving computing system for controllingvehicle 100.

As an example, computing devices 110 may interact with one or moreactuators of the deceleration system 160 and/or acceleration system 162,such as brakes, accelerator pedal, and/or the engine or motor of thevehicle, in order to control the speed of the vehicle. Similarly, one ormore actuators of the steering system 164, such as a steering wheel,steering shaft, and/or pinion and rack in a rack and pinion system, maybe used by computing devices 110 in order to control the direction ofvehicle 100. For example, if vehicle 100 is configured for use on aroad, such as a car or truck, the steering system may include one ormore actuators to control the angle of wheels to turn the vehicle.Signaling system 166 may be used by computing devices 110 in order tosignal the vehicle's intent to other drivers or vehicles, for example,by lighting turn signals or brake lights when needed.

Navigation system 168 may be used by computing devices 110 in order todetermine and follow a route to a location. In this regard, thenavigation system 168 and/or data 132 may store detailed mapinformation, e.g., highly detailed maps identifying the shape andelevation of roadways, lane lines, intersections, crosswalks, speedlimits, traffic signals, buildings, signs, real time trafficinformation, vegetation, or other such objects and information.

FIG. 2 is an example of map information 200 for a section of roadwayincluding intersections 202 and 204. In this example, the mapinformation 200 includes information identifying the shape, location,and other characteristics of lane lines 210, 212, 214, traffic signallights 220, 222, crosswalk 230, sidewalks 240, stop signs 250, 252, andyield sign 260. Areas where the vehicle can drive may be associated withone or more rails 270, 272, and 274 which indicate the location anddirection in which a vehicle should generally travel at variouslocations in the map information. For example, a vehicle may follow rail270 when driving in the lane between lane lines 210 and 212, and maytransition to rail 272 in order to make a right turn at intersection204. Thereafter the vehicle may follow rail 274. Of course, given thenumber and nature of the rails only a few are depicted in mapinformation 200 for simplicity and ease of understanding.

Although the map information is depicted herein as an image-based map,the map information need not be entirely image based (for example,raster). For example, the map information may include one or moreroadgraphs or graph networks of information such as roads, lanes,intersections, and the connections between these features. Each featuremay be stored as graph data and may be associated with information suchas a geographic location and whether or not it is linked to otherrelated features, for example, a stop sign may be linked to a road andan intersection, etc. In some examples, the associated data may includegrid-based indices of a roadgraph to allow for efficient lookup ofcertain roadgraph features.

Positioning system 170 may be used by computing devices 110 in order todetermine the vehicle's relative or absolute position on a map or on theearth. For example, the position system 170 may include a GPS receiverto determine the device's latitude, longitude and/or altitude position.Other location systems such as laser-based localization systems,inertial-aided GPS, or camera-based localization may also be used toidentify the location of the vehicle. The location of the vehicle mayinclude an absolute geographical location, such as latitude, longitude,and altitude as well as relative location information, such as locationrelative to other cars immediately around it which can often bedetermined with less noise that absolute geographical location.

The positioning system 170 may also include other devices incommunication with computing devices 110, such as an accelerometer,gyroscope or another direction/speed detection device to determine thedirection and speed of the vehicle or changes thereto. By way of exampleonly, an acceleration device may determine its pitch, yaw or roll (orchanges thereto) relative to the direction of gravity or a planeperpendicular thereto. The device may also track increases or decreasesin speed and the direction of such changes. The device's provision oflocation and orientation data as set forth herein may be providedautomatically to the computing devices 110, other computing devices andcombinations of the foregoing.

The perception system 172 also includes one or more components fordetecting objects external to the vehicle such as other vehicles,obstacles in the roadway, traffic signals, signs, trees, etc. Forexample, the perception system 172 may include lasers, sonar, radar,cameras and/or any other detection devices that record data which may beprocessed by computing device 110. In the case where the vehicle is apassenger vehicle such as a minivan, the minivan may include a laser orother sensors mounted on the roof or other convenient location. Forinstance, FIG. 3 is an example external view of vehicle 100. In thisexample, roof-top housing 310 and dome housing 312 may include a lidarsensor as well as various cameras and radar units. In addition, housing320 located at the front end of vehicle 100 and housings 330, 332 on thedriver's and passenger's sides of the vehicle may each store a lidarsensor. For example, housing 330 is located in front of driver door 360.Vehicle 100 also includes housings 340, 342 for radar units and/orcameras also located on the roof of vehicle 100. Additional radar unitsand cameras (not shown) may be located at the front and rear ends ofvehicle 100 and/or on other positions along the roof or roof-top housing310.

The computing devices 110 may control the direction and speed of thevehicle by controlling various components. By way of example, computingdevices 110 may navigate the vehicle to a destination locationcompletely autonomously using data from the detailed map information andnavigation system 168. Computing devices 110 may use the positioningsystem 170 to determine the vehicle's location and perception system 172to detect and respond to objects when needed to reach the locationsafely. In order to do so, computing devices 110 may cause the vehicleto accelerate (e.g., by increasing fuel or other energy provided to theengine by acceleration system 162), decelerate (e.g., by decreasing thefuel supplied to the engine, changing gears, and/or by applying brakesby deceleration system 160), change direction (e.g., by turning thefront or rear wheels of vehicle 100 by steering system 164), and signalsuch changes (e.g., by lighting turn signals of signaling system 166).Thus, the acceleration system 162 and deceleration system 160 may be apart of a drivetrain that includes various components between an engineof the vehicle and the wheels of the vehicle. Again, by controllingthese systems, computing devices 110 may also control the drivetrain ofthe vehicle in order to maneuver the vehicle autonomously.

Example Methods

In addition to the operations described above and illustrated in thefigures, various operations will now be described. It should beunderstood that the following operations do not have to be performed inthe precise order described below. Rather, various steps can be handledin a different order or simultaneously, and steps may also be added oromitted.

When operating in the autonomous driving mode, as the vehicle movesthrough its environment, the perception system 172 may send thecomputing devices 110 sensor data identifying objects in the vehicle'senvironment as well as their characteristics. This information may becombined with feedback information from the vehicle's various systems aswell as the map information in order to determine how to maneuver thevehicle through its environment. As part of this, the computing devices110 may generate a trajectory for the vehicle to follow through itsenvironment for some period into the future. This trajectory may includecontrol requirements for the position and speed of the vehicle atdifferent times during the period. For example, a trajectory may includea geometry component and a speed component. The geometry component maydefine one or more future positions of the vehicle at different timesduring the period while the speed component may define one or morefuture speeds of the vehicle at different times during the period.

For instance, FIG. 4 depicts vehicle 100 being maneuvered on a sectionof roadway 400 including intersections 402 and 404. In this example,intersections 402 and 404 correspond to intersections 202 and 204 of themap information 200, respectively. In this example, lane lines 410, 412,and 414 correspond to the shape, location, and other characteristics oflane lines 210, 212, and 214, respectively. Similarly, crosswalk 430corresponds to the shape, location, and other characteristics ofcrosswalk 230, respectively; sidewalks 440 correspond to sidewalks 240;traffic signal lights 420, 422 correspond to traffic signal lights 220,222, respectively; stop signs 450, 452 correspond to stop signs 250,252, respectively; and yield sign 460 corresponds to yield sign 260. Inthis example, the computing devices 110 have used map information 200 todetermine a trajectory 470 for vehicle 100 to follow in order to reach adestination (not shown). In this example, trajectory 470 includes aspeed component and geometry component (same as what is shown in FIG. 4for trajectory 470) that will require that vehicle 100 may a left turnat intersection 404.

In order to proceed along the trajectory 470, the computing devices 110may use the trajectory to generate and send signals including commandsto the various actuators of the vehicle, including for instance,steering orientation signals with steering orientation commands to theone or more steering actuators, acceleration signals with accelerationcommands to the one or more acceleration actuators, and/or decelerationsignals with deceleration commands to the one or more decelerationactuators. For instance, as shown in FIG. 5, computing devices 110 sendsignals 510 to each of the one or more deceleration actuators of thedeceleration system 160, one or more acceleration actuators of theacceleration system 162, and one or more steering actuators of thesteering system 164 as needed in order to follow trajectory 470. Theactuators, in turn, may cause the vehicle to control the orientation,acceleration, and deceleration of the vehicle according to the commandsto follow the trajectory.

In some instances, the driver may want to take control of one or more ofthe steering, acceleration, and deceleration from the computing devices110. As an example, returning to FIG. 4, the driver may want to make theturn at intersection 404 more quickly, or may be concerned that thevehicle is going to take the turn and come too close to another vehicleor object. Of course, the driver may simply want to take control of thevehicle “just because” or for any number of reasons.

For instance as shown in FIG. 6 and noted above, this may be achieved bythe driver using one of input devices 600, such as a steering wheel,accelerator pedal or brake pedal. In this regard, the driver may use oneor more of the input devices 600 of the vehicle to request control ofthe vehicle, or rather, that the vehicle switch from the autonomous modeto the manual driving mode. The one or more input devices, dependingupon which one or more are used by the driver, then send signals 610 toone or more of the one or more deceleration actuators of thedeceleration system 160, one or more acceleration actuators of theacceleration system 162, or one or more steering actuators of thesteering system 164. For instance, the driver may use input devicesincluding both an accelerator pedal and steering wheel, which may sendsignals to each of the acceleration actuators and steering actuators.Similarly, the driver may use input devices including both a brake pedaland steering wheel, which may send signals to each of the decelerationactuators and steering actuators. Alternatively, the driver may use onlya single input device, such as a brake pedal, accelerator pedal, orsteering wheel. In this regard, the single input device may send asignal to the corresponding actuators.

Although not shown in the figures, vehicle 100 may include additionalredundant features and systems. This may include systems to send controlsignals, redundant input devices and systems (for instance forrequesting a transition to a manual mode), redundant braking, steering,and acceleration systems, etc.

Once the driver initiates this input, the computing devices 110 may alsoreceive one or more signals 620 indicating that the driver requests totake control of the vehicle. For instance the signals 620 may indicatethat the driver wants to transition into a manual driving mode or asemiautonomous mode (where the computing devices 110 continue to controlat least one of steering, acceleration or deceleration). For simplicity,the transitions described herein relate to transitions from theautonomous driving mode to a manual driving mode, though othertransitions may also be used and would function in similar ways, thoughthe computing devices 110 would retain control of at least one of thesteering, acceleration, and deceleration after a transition perioddiscussed further below.

In response to the signal indicating that the driver requests to takecontrol of the vehicle, the computing devices 110 may begin totransition control of the steering, acceleration, and decelerationsystems to the driver and thereby transition the vehicle to the manualdriving mode (or semiautonomous mode). This transition may occur duringa transition period. During the transition period, the computing devices110 may send signals to the actuators, as shown in the example of FIG.5, indicating that the vehicle is transitioning to the manual drivingmode. In response, the actuators may themselves transition to the manualdiving mode whereby the actuators will not accept or act upon additionalcommands from the computing devices 110 until the vehicle transitionsback to the autonomous driving mode. Once the transition period iscomplete, only inputs from the driver will be used to control thevehicle in the manual driving mode.

As noted above, in some instances, the driver input indicating that thedriver would like to switch from the autonomous driving mode to themanual driving mode may occur while the computing devices 110 aresending signals to the actuators of the steering, acceleration ordeceleration systems. For instance, signals may be sent to the vehicle'sone or more deceleration actuator to decelerate or cause the vehicle tobrake in order to reduce the speed of the vehicle prior to making theturn in order to follow trajectory 470. In addition, signals may also besent to the vehicle's one or more steering actuators to change theorientation of the vehicle in order to follow trajectory 470.

As noted above, when these signals are ceased during the transition, theresulting reduction in deceleration of the vehicle can actually feel tothe driver as if the vehicle is inappropriately understeering,deceleration or accelerating depending upon the situation. For instance,if the computing devices 110 are sending deceleration signals to the oneor more deceleration actuators which are causing the vehicle todecelerate, and the driver wants the vehicle to brake harder, the drivermay attempt to transition the vehicle to the manual driving mode byusing the brake pedal. However, there may be a delay between when theone or more deceleration actuators stop receiving deceleration signalsfrom the computing devices 110 and when the one or more decelerationactuators are able to receive and act upon the driver input from thebrake pedal. As a result, for a brief period, the driver may feel as ifthe vehicle is actually accelerating, even though it is merely areduction in the amount of deceleration. This can be especiallyuncomfortable for a driver where the transition is a result of thedriver feeling the need to take control of the vehicle in a situation inwhich the driver feels additional braking is necessary (i.e. the driveris concerned that a collision may occur, etc.).

In order to assist the driver during this transition period, additionalsteering, acceleration and/or deceleration signals may be sent to thevehicle's various actuators after the driver uses the input devices torequest that the vehicle transition to the manual driving mode. Forinstance, these additional signals may cause the actuators to continueto control the vehicle according to the trajectory, decelerating,accelerating and steering, for some brief period of time. This reducesthe feeling of the driver that the vehicle is understeering,decelerating, or accelerating when the driver is given control of thevehicle.

These additional signals may actually continue during and even after thetransition period until the computing devices 110 recognize the driver'sintention or desire to disengage the autonomous mode before or when thedriver commanded steering, acceleration, or braking reaches the samemagnitude as the control computing devices were previously commanding.This timing can be tuned to feel “natural” and comfortable to a driver,again in order to reduce the feeling that the vehicle is understeering,decelerating, or accelerating when the driver is given control of thevehicle.

For instance, the additional signals may be continued according to thecontrol computing device's current trajectory plan for the vehicle forsome brief period into the future, such as 1 or 2 seconds or more orless, or until the input from the driver is received by the steering,deceleration or acceleration actuators and acted upon by those actuatorsas described above. In this regard, signals received by the vehicle'sactuators from the input devices may “overrule” signals from thecomputing devices 110.

In addition, the additional signals sent may or may not be dependentupon which input the driver uses to transition control of the vehicle.For example, if the vehicle was in the middle of swerving to avoid anobstacle, and a driver stepped on the brake, the vehicle may smoothlytransition control of the steering actuator as well as the decelerationactuator.

Alternatively, the additional signals that are sent to the vehicle'sactuator(s) may include different instructions depending on the type ofinput by the driver at the input for steering, acceleration ordeceleration. In this regard, if the driver attempts to transition fromthe autonomous driving mode to the manual driving mode by using thesteering input, deceleration input or acceleration input, the force ofthe input (if a brake or acceleration pedal) as well as the distance theinput is moved may be used to determine how the signals are continued.For instance, the magnitude if the force on a brake or accelerationpedal may be measured using a force input device, and this informationmay be sent back to the computing devices 110. Similarly, the distancethe brake or acceleration pedal is moved or the change in orientation ofthe steering wheel may be measured using a distance or angularmeasurement device, and this information may be sent back to thecomputing devices 110. The computing devices 110 may then use thisinformation to determine what signals to send to any of the vehicle'sactuators.

As an example, if the driver only lightly pushes, for instance with verylittle force, on the brake pedal such that is moves only a shortdistance, the additional deceleration signals may cause the decelerationactuator to continue only a small amount of deceleration of the vehicle.In other words, the amount of deceleration would less than what thecomputing devices 110 would have signaled to the one or moredeceleration actuators if the transition had not occurred. Similarly, ifthe driver uses much more force on the brake pedal, such that the brakepedal moves a greater distance, the additional deceleration signals maycause the deceleration actuator to continue the same amount ofdeceleration of the vehicle. In some instances, the additionaldeceleration signals may increase the deceleration of the vehicle if theforce on the brake pedal and/or the distance moved is very great.

The additional signals can also be adjusted according to theconfiguration of the vehicle. For instance, if the computing devices 110are able to directly control the deceleration and acceleration actuators(i.e. by physically moving the pedals), rather than indirectly bysending signals through the inputs used by the driver, the position ofthe brake pedal may be such that the pedal is already in a brakingposition when the driver uses the pedal. In such examples, theadditional signals may not be needed or may be phased out quicker.

In some situations in which the vehicle is moving slowly or acceleratingslowly, the driver may not even notice the additional steering,acceleration or braking commands. In other words, the change in thesteering orientation caused by the lack of continued steering signals,the change in the acceleration caused by the lack of continuedacceleration signals, and/or the change in the deceleration caused bythe lack of continued braking signals would be very small or such thatthe driver may not notice. In this regard, the additional signals mayalways be sent or may be sent only when the commands within the signalsbeing sent by the computing devices 110 to the vehicle's actuators meetcertain thresholds. For instance, the computing devices 110 may onlysend additional signals if the current signals include commands for theone or more deceleration actuators to decelerate the vehicle at acertain rate, for the one or more acceleration actuators to acceleratethe vehicle at a certain rate, or for the one or more steering actuatorsto change the orientation of the vehicle at a certain rate.

FIG. 7 includes an example flow diagram 700 of some of the examplesmethods for controlling a transition between a manual driving mode andan autonomous driving mode of a vehicle as described above. In thisexample, the steps of flow diagram may be performed by one or moreprocessors of one or more computing devices, such as processors 120 ofcomputing devices 110. In this example, at block 710, the vehicle iscontrolled in the autonomous driving mode. While controlling the vehiclein the autonomous driving mode and decelerating at a given rate, inputrequesting a transition from the autonomous driving mode to the manualdriving mode is received at a user input of the vehicle at block 720. Inresponse to the input, the vehicle is transitioned to the manual drivingmode at block 730. After transitioning the vehicle to the manual drivingmode, deceleration signals are sent to a deceleration actuator therebycausing the vehicle to continue to decelerate at the given rate at block740.

Unless otherwise stated, the foregoing alternative examples are notmutually exclusive, but may be implemented in various combinations toachieve unique advantages. As these and other variations andcombinations of the features discussed above can be utilized withoutdeparting from the subject matter defined by the claims, the foregoingdescription of the embodiments should be taken by way of illustrationrather than by way of limitation of the subject matter defined by theclaims. In addition, the provision of the examples described herein, aswell as clauses phrased as “such as,” “including” and the like, shouldnot be interpreted as limiting the subject matter of the claims to thespecific examples; rather, the examples are intended to illustrate onlyone of many possible embodiments. Further, the same reference numbers indifferent drawings can identify the same or similar elements.

The invention claimed is:
 1. A method of controlling a transitionbetween a manual driving mode and an autonomous driving mode of avehicle, the method comprising: controlling, by one or more processorsof one or more control computing devices, the vehicle in the autonomousdriving mode; while controlling the vehicle in the autonomous drivingmode and decelerating at a given rate, receiving, by the one or moreprocessors at a user input of the vehicle, input requesting a transitionfrom the autonomous driving mode to the manual driving mode; in responseto the input, transitioning the vehicle to the manual driving mode; andafter transitioning the vehicle to the manual driving mode, sending, bythe one or more processors over a given period, deceleration signals toa deceleration actuator thereby causing the vehicle to continue todecelerate at the given rate during the given period.
 2. The method ofclaim 1, further comprising, after receiving the input, determining thatthe one or more control computing devices are currently causing thevehicle to decelerate, and wherein the given period over which thedeceleration signals are sent is based on the determination that thecontrol computing devices are currently causing the vehicle todeceleration.
 3. The method of claim 2, further comprising, afterdetermining that the one or more control computing devices are currentlycausing the vehicle to decelerate, comparing an amount of decelerationcurrently requested by the control computing devices to a thresholddeceleration, and wherein the given period over which the decelerationsignals are sent is further based on the comparison.
 4. The method ofclaim 1, further comprising, identifying a distance that user input hasmoved to cause the input, and wherein the given period over which thedeceleration signals are sent is based on the distance.
 5. The method ofclaim 1, further comprising, identifying a force on the user input tocause the input, and wherein the given period over which thedeceleration signals are sent is based on a magnitude of the force. 6.The method of claim 1, wherein the given period over which thedeceleration signals are sent is based upon a current plan of operationby the one or more control computing devices when that the input isreceived.
 7. The method of claim 1, wherein the given period over whichthe deceleration signals are sent to the deceleration actuator is basedupon the time required for a deceleration signal initiated by input at adeceleration pedal of the vehicle to reach the deceleration actuator. 8.The method of claim 1, wherein the given period over which thedeceleration signals are sent to the deceleration actuator is based uponthe time required for an acceleration signal initiated by user input ata deceleration pedal of the vehicle to reach an acceleration actuator ofthe vehicle that causes the vehicle to accelerate.
 9. The method ofclaim 1, wherein the user input is a steering wheel of the vehicle. 10.The method of claim 1, wherein the user input is a brake pedal of thevehicle.
 11. The method of claim 1, wherein while controlling thevehicle in the autonomous driving mode and decelerating at the givenrate, the vehicle is also changing orientation at a second given rate,and wherein the method further comprises, after transitioning thevehicle to the manual driving mode, sending, by the one or moreprocessors, steering orientation signals to a steering actuator therebycausing the vehicle to continue to change orientation at the secondgiven rate.
 12. A system for controlling a transition between a manualdriving mode and an autonomous driving mode of a vehicle, the systemcomprising one or more processors configured to: control the vehicle inthe autonomous driving mode; while controlling the vehicle in theautonomous driving mode and decelerating at a given rate, receive, at auser input of the vehicle, input requesting a transition from theautonomous driving mode to the manual driving mode; in response to theinput, transition the vehicle to the manual driving mode; and aftertransitioning the vehicle to the manual driving mode, send decelerationsignals to a deceleration actuator for a given period thereby causingthe vehicle to continue to decelerate at the given rate during the givenperiod.
 13. The system of claim 12, wherein the one or more processorsare further configured to, after receiving the input, determine that theone or more control computing devices are currently causing the vehicleto decelerate, and wherein the given period over which decelerationsignals are sent is based on the determination that the one or morecontrol computing devices are currently causing the vehicle todeceleration.
 14. The system of claim 13, wherein the one or moreprocessors are further configured to, after determining that the one ormore control computing devices are currently causing the vehicle todecelerate, compare an amount of deceleration currently requested by theone or more control computing devices to a threshold deceleration, andwherein the given period over which the deceleration signals are sent isfurther based on the comparison.
 15. The system of claim 12, wherein theone or more processors are further configured to, identify a distancethat user input has moved to cause the input, and wherein the givenperiod over which the deceleration signals are sent is based on thedistance.
 16. The system of claim 12, wherein the one or more processorsare further configured to identify an amount of force on the user inputto cause the input, and wherein the given period over which thedeceleration signals are sent is based on the amount of force.
 17. Thesystem of claim 12, wherein the fixed period over which the one or moreprocessors continue to send the deceleration signals to the decelerationactuator is based upon the time required for a deceleration signalinitiated by input at a deceleration pedal of the vehicle to reach thedeceleration actuator.
 18. The system of claim 12, wherein the fixedperiod over which the one or more processors continue to send thedeceleration signals to the deceleration actuator is based upon the timerequired for an acceleration signal initiated by user input at adeceleration pedal of the vehicle to reach an acceleration actuator ofthe vehicle that causes the vehicle to accelerate.
 19. The system ofclaim 12, wherein while controlling the vehicle in the autonomousdriving mode and decelerating at the given rate, the vehicle is alsochanging orientation at a second given rate, and wherein the one or moreprocessors are further configured to, after transitioning the vehicle tothe manual driving mode, send steering orientation signals to a steeringactuator thereby causing the vehicle to continue to change orientationat the second given rate.
 20. The system of claim 12, further comprisingthe vehicle.